Some conventional vehicular lamps have been known to include a light source with a light emitting device and a guiding lens (translucent member) configured to guide the light emitted from the light source. Examples of this type of vehicular lamp have been described in, for example, Japanese Patent Application Laid-Open No. 2005-203111 or U.S. Pat. No. 7,270,454(B2) (hereinafter, referred to as Patent Literature 1), in particular, FIGS. 1 to 3. The vehicular lamp disclosed in Patent Literature 1 has a light source having a light emitting device with an optical axis extending horizontally. Light emitted from the light source can be guided by the guiding lens (translucent member) to be partially radiated in the optical axis direction of the light source.
In particular, the vehicular lamp described in FIGS. 1 to 3 of Patent Literature 1 includes the guiding lens (translucent member) having: a first incidence face on which the light emitted from the light source at a first angle with respect to the optical axis of the light source is incident; a first light-exiting face through which the light from the first incidence face passes to be projected in the illumination direction of the vehicular lamp; a second incidence face on which the light emitted from the light source at a second angle larger than the first angle with respect to the optical axis and the light emitted from the light source at a third angle larger than the second angle with respect to the optical axis is incident; a first reflection face configured to reflect the light emitted from the light source at the second angle and having passed through the second incidence face, in the optical axis direction of the light source; a second light-exiting face through which the light from the first reflection face passes to be projected in the illumination direction of the vehicular lamp; a second reflection face configured to reflect the light emitted from the light source at the third angle and having passed through the second incidence face, in the optical axis direction of the light source; a third light-exiting face through which the light from the second reflection face passes to be projected in the illumination direction of the vehicular lamp; a reflection face-side connection face configured to connect the first reflection face with the second reflection face; and a light-exiting face-side connection face configured to connect the second light-exiting face with the third light-exiting face.
In the vehicular lamp disclosed in FIGS. 1 to 3 of Patent Literature 1, the outline of the guiding lens when viewed from the front side in the optical axis direction of the light source can be a circle. However, in order to enhance the aesthetic or designing value of a vehicular lamp, it may be required to form the guiding lens with a polygonal outline when viewed from the optical axis direction.
In order to comply with such a requirement, it is conceivable that such a guiding lens can be formed by the following designing process. Specifically, a rotational body for a guiding lens can be obtained by rotating a cross-section on a plane containing the optical axis of the light source around the optical axis by 360 degrees, and the rotational body is cut along a desired polygonal outline to obtain the desired guiding lens.
When a guiding lens is formed by the above designing process, however, light-exiting face-side connection faces configured to connect a plurality of light-exiting faces may be located on a plurality of sides of the polygon at a higher possibility rather than the light-exiting faces themselves are located thereon. Since the light-exiting face-side connection faces cannot be seen to emit light when viewed from the front side in the optical axis direction, if the light-exiting face-side connection faces are located on the polygon sides at a high possibility, the polygon sides of the guiding lens may be seen darker at a high possibility when viewed from the front side in the optical axis direction. Accordingly, when the guiding lens is designed by the above designing process, the resulting guiding lens may have a blurred outline of the polygon of the guiding lens when viewed from the front side in the optical axis direction.
Furthermore, this means that at the positions where the light-exiting face-side connection faces are located on the polygonal sides, there are no light-exiting faces configured to allow the light guided by the guiding lens to be projected therethrough in the illumination direction of the vehicular lamp. Accordingly, the light guided by the guiding lens to those positions cannot be projected in the illumination direction of the vehicular lamp. This may deteriorate the use efficiency of light emitted from the light source.